Zenith SF3537H modules wanted

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Re: Zenith SF3537H modules wanted
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Will you return the duds in the suplied boxes, with the form filled out  
for your credit?

Re: Zenith SF3537H modules wanted
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Heh, I think they want to fix it because it weighs around 270 pounds and
it's a struggle to move around.

I used to own the same model and it cost me $20 for a couple mexicans to
dump it somewhere.

It's from the early 90's and has a piss poor picture compared to even the
cheapest lcd/led tv currently on the market. I think that one had the
"teletext" service built into it.

Got that one straight out of the Zenith employee store when they had the
plant on North Ave and the 294. Was supposed to be a life-test set but  
someone really failed, even though it was supposed to have the "Premium
Sound" package, it sounded like a $10 clock radio. A couple years on I  
opened the back for something and the entire sub-woofer amplifier module
was missing. Just a couple connectors laying where the module went. Oddly
enough the sub-woofers were there, just missing the amp for them.

How they q/c'ed that for resale is beyond me.

-bruce
snipped-for-privacy@ripco.com


Re: Zenith SF3537H modules wanted
On Wednesday, September 9, 2020 at 7:03:30 AM UTC-4, snipped-for-privacy@ripco.com wrote:
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I sold a few of those, and they were absolute toilets.  Zenith had some goo
d tech back then but the Digital System Three wasn't any part of it.  IIRC,
 it was based on the ITT digital TV chipset.  They were squirrely when they
 were new and had a terrible muddy picture no matter how carefully they wer
e prepped.  On a blank snowy channel,  these showed poor color temperature  
and bloated and blurry"pop corn" snow whereas every other TV back then had  
crisp, tight snow with excellent color temp.  I can't guess why anyone woul
d want to fix one of these unless it was for a historic collection of some  
sort.


Re: Zenith SF3537H modules wanted
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od tech back then but the Digital System Three wasn't any part of it. IIRC,
 it was based on the ITT digital TV chipset. They were squirrely when they  
were new and had a terrible muddy picture no matter how carefully they were
 prepped. On a blank snowy channel, these showed poor color temperature and
 bloated and blurry"pop corn" snow whereas every other TV back then had cri
sp, tight snow with excellent color temp. I can't guess why anyone would wa
nt to fix one of these unless it was for a historic collection of some sort
.

Re: Zenith SF3537H modules wanted
:
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od tech back then but the Digital System Three wasn't any part of it. IIRC,
 it was based on the ITT digital TV chipset. They were squirrely when they  
were new and had a terrible muddy picture no matter how carefully they were
 prepped. On a blank snowy channel, these showed poor color temperature and
 bloated and blurry"pop corn" snow whereas every other TV back then had cri
sp, tight snow with excellent color temp. I can't guess why anyone would wa
nt to fix one of these unless it was for a historic collection of some sort
.

Re: Zenith SF3537H modules wanted
I have never have not had those problems with my tv since it was new





On Wednesday, September 9, 2020 at 2:19:11 PM UTC-5, snipped-for-privacy@gmail.com wrote
:
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od tech back then but the Digital System Three wasn't any part of it. IIRC,
 it was based on the ITT digital TV chipset. They were squirrely when they  
were new and had a terrible muddy picture no matter how carefully they were
 prepped. On a blank snowy channel, these showed poor color temperature and
 bloated and blurry"pop corn" snow whereas every other TV back then had cri
sp, tight snow with excellent color temp. I can't guess why anyone would wa
nt to fix one of these unless it was for a historic collection of some sort
.

Re: Zenith SF3537H modules wanted
On Wednesday, September 9, 2020 at 5:19:15 PM UTC-4, snipped-for-privacy@gmail.com wro
te:
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The Digital System 3 is simply a poor performer and they were when they wer
e brand new.  When showing them, we had to make sure every other TV in the  
showroom was off, including the basic and far cheaper analog System 3 and C
hromacolor Zeniths which badly outperformed them at 50% the cost.  The DS3  
TV was built as a true digital TV and was the first with no mechanical chas
sis adjustments other than F, G2, and ring magnets around the CRT.  While c
ertainly noteworthy in a historical context, as an instrument to view telev
ision, they were also noteworthy in a bad way.

I used to have a bin full of all the 700 board chips (many several deep), s
everal 700 boards (the rest of the boards were reliable) and threw them all
 away about 20 years ago when we put those chassis on the verboten list bec
ause of reliability and performance reasons.  Half the 700 boards we got fr
om Zenith in the red label (rebuilt) boxes didn't work or didn't work prope
rly, and the yellow label (new) boards were exhausted when the TVs were sti
ll in warranty.

Honestly, if you want to keep it running for historical or even sentimental
 reasons, I couldn't argue with that and wish you luck on your parts search
.  But if you want to watch programs on it, you would be better off with li
terally any other CRT TV of any era, including vacuum tube TVs that precede
d it.


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good tech back then but the Digital System Three wasn't any part of it. IIR
C, it was based on the ITT digital TV chipset. They were squirrely when the
y were new and had a terrible muddy picture no matter how carefully they we
re prepped. On a blank snowy channel, these showed poor color temperature a
nd bloated and blurry"pop corn" snow whereas every other TV back then had c
risp, tight snow with excellent color temp. I can't guess why anyone would  
want to fix one of these unless it was for a historic collection of some so
rt.

Re: Zenith SF3537H modules wanted
snipped-for-privacy@ripco.com wrote:
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This seller accidentally listed one as shipped with USPS first class  
package

https://www.ebay.com/itm/zenith-tv-35-1990-SF3537H-/203031486909

It like how it's posed on that jack thing for moving heavy, annoyingstuff.  
Heck, that cabinet is big enough just to fit a last run Panasonic CRT  
television inside of. Not even kidding either. Might be a fun project.
  
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Just have been an "honest" mistake. Any idea where they rebuilt all those  
modules you had to swap? I kind of liked their 70s console TVs with the  
weird plastic pedastal and the preposterous "zoom" button.

Re: Zenith SF3537H modules wanted

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Pffft. Foggy memories of that stuff.

I think, when I decided to look at the sound problem I went over to that
place on Bryn Mawr just west of Kimball, North Central. They used to be
authorized Zenith, RCA, Magnavox and some others distributors.

I ordered the service manual and when it came in I remember the guy behind
the counter said I wasn't going to like it. Not sure if it was from Zenith
or the Sams copy but it basically was a single "road map", folded out to
like a 3'x4' paper that was more or less just a block diagram of the set.

Very few voltage reading points and or waveforms. Most of it was covered in
"gray areas" and he said if you think the problem was in one of those areas,
Zenith wanted the whole module back for diagnostics.

So I'm assuming at least through the mid 90's all the defective modules went
back to them.

Later on, after LG took them over and Phillips took over RCA, there was a
mail order place to get modules in Indiana, pretty sure they were called
PTS, a place that used to repair detent (mechanical) vhf/uhf tuners. After
those became extinct, they went into the module repair/replacement business.

Pretty sure PTS stood for Precision Tuner Service but after a quick google,
they don't seem to be around anymore or have a historical mention.

Might of been PTC, like I said, foggy memory of all that now.

Anyway, with those Digital System III's (or whatever they were called),
Zenith never wanted board level repairs on them. Just module exchanges.

-bruce
snipped-for-privacy@ripco.com

Re: Zenith SF3537H modules wanted
On Mon, 12 Oct 2020 12:51:58 -0000 (UTC), snipped-for-privacy@ripco.com wrote:

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It was PTS. At one point, they had offices in most major US cities.
Thomson bought RCA, not Phillips.

Re: Zenith SF3537H modules wanted
On Monday, October 12, 2020 at 1:10:53 PM UTC-4, Chuck wrote:
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Also, PTS started out as Precision Tuner Service.  There were a dozen or mo
re similar companies in the U.S., like Castle Tuner Service.  They started  
out servicing mechanical tuners, then electronic tuners, then expanded to T
V modules.  PTS still exists as a recycler that sells used boards: https://
www.ptselectronicsinc.com/

Re: Zenith SF3537H modules wanted
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What's involved in the rebuild of a manual tuner? A spray of tuner cleaner  
or something like that was all I ever did the few times I came across one.

Anyone recall the freon ban and folks buying CASES of the stuff like blue  
shower and the freezy spray because all the substitutes were trash?


Re: Zenith SF3537H modules wanted
On Thursday, October 15, 2020 at 2:13:24 AM UTC-4, Cydrome Leader wrote:
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r more similar companies in the U.S., like Castle Tuner Service.  They star
ted out servicing mechanical tuners, then electronic tuners, then expanded  
to TV modules.  PTS still exists as a recycler that sells used boards: http
s://www.ptselectronicsinc.com/
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A marginal mechanical tuner used to work find on a cable box or even a broa
d spectrum manual cable system.  Back when everything was on antenna, the t
uner was critical to performance of the TV, but when fed with a strong sign
al, cable, RF modulator, less so.

Better rebuilders would dip-clean the chassis, replace the wafer switches i
f bad, replace any bad parts inside (really tight for room on the increment
al types), clean and lube the contacts, and align them.  Later, they replac
ed transistors when the tuners went SS.  Honestly, for $7.95 U.S., it wasn'
t worth screwing with them.  They would come back rock solid and aligned. T
owards the end of the mechanical tuner era, they were still less than $20 t
o get rebuilt.  

Re: Zenith SF3537H modules wanted
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Many decades ago (in my high-school days) I did a bit of TV-tuner
servicing.  The VHF-channel tuners used a turret design - rotating the
knob into position rotated a channel-specific resonator on the turret
into the contact position.  Each resonator had a fine-tuning reactance
(either a movable-slug inductor or a variable capacitor, I don't
recall which), whose adjusting shaft ended in a plastic gear that
meshed with the "fine tune" control (typically a ring running around
the outside of the channel knob).

Over time, the plastic gears on the turret, and the plastic gear or
planetary ring on the fine-tune control would wear, and they wouldn't
mesh properly.  As I recall, the failure would usually occur when the
fine-tuning adjustment was rotated to one end of its range - the
control teeth would no longer mesh with the worn ends of the teeth on
the turret gear, and the fine-tune control would be "stuck" for that
channel (typically at a position where the channel wasn't watchable).

I could clean the turret contacts well enough, and manually return the
worn-gear "stuck" channel adjustments back to a point where they'd
mesh with the control gearing and work again, but the problem would
recur if somebody rotated the fine-tuning knob too far once again.

A real rebuild would have required replacing all of the worn gears.  I
didn't have the ability to do that, at the time.





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